Revert merge request #139

As well reported on the bug report #153, there was a side effect by applying this patch. This side effect was caused due to a race condition while cleaning and creating a new instance of the ModSecurity standalone implementation. Sometimes the second instance was freed instead of the first. Leaving the resource utilized by the first instance occupied, however, in a inconsistent way, leading ModSecurity to fail.

The first reported bug (#137) which this patch was made to fix, is not so critical in the sense that it does not leave the ModSecurity to fail straight. Having said that I am now reverting this fix, opening again the issue #137.